This invention relates to the production of alkenylthiophenols, e.g., para-vinylthiophenol, and their esters, e.g., para-vinylthiophenol acetate.
Alkenylthiophenols, e.g., para-vinylthiophenol, and their esters, have utility as monomers in the formation of sulfur-containing graft polymers and copolymers having various end uses. For example, alkenylthiophenol esters, e.g., para-vinylthiophenol acetate (or para-vinylphenylthiol acetate), are suitable sulfur-containing monomers for the production of graft copolymers which, after hydrolysis, are useful in the formation of rubber reinforcing elements having superior adhesion to rubber; see for example, U.S. Pat. No. 3,475,251 issued Oct. 28, 1969 to Widmer. These sulfhydryl containing monomers are also suitable for the production of resins useful for the extraction of metals such as mercury and lead; see for example, P.A. Schweitzer, Handbook of Separation Techniques for Chemical Engineers (McGraw-Hill), page 1-386 (one page).
Newman et al, Journal of Organic Chemistry 31, 3980-3984 (1966), teach the formation of O-aryl dialkylthiocarbamates by reaction of a phenol with a dialkyl thiocarbamoyl chloride, and the pyrolytic rearrangement of O-aryl dialkylthiocarbamates to S-aryl dialkylthiocarbamates. Specifically disclosed in Table I is the pyrolytic rearrangement of O-(4'-acetophenyl) dimethylthiocarbamate to S-(4'-acetophenyl) dimethylthiocarbamate.
Newman et al, U.S. Pat. No. 3,476,791, disclose a process similar to that disclosed in the article cited in the preceding paragraph and was issued to patentees who are the same as the authors of such article. Example 14 of the patent shows the preparation of p-acetylphenyl dimethylthiolcarbamate from p-acetylphenyl dimethylthioncarbamate.
Kwart et al, Journal of Organic Chemistry 31, 410-413 (1966), show the vapor phase pyrolytic rearrangement of various diaryl thioncarbonates to O,S-diaryl thiolcarbonates and of various O-aryl dialkylthioncarbamates to S-aryl dialkylthiolcarbamates.
Overberger et al, Journal of the American Chemical Society 78, 4792-4797 (1956), teach the preparation of p-vinylphenyl thioacetate by diazotizing p-aminoacetophenone and reacting the diazonium compound with potassium ethyl xanthate to form ethyl p-acetylphenyl xanthate. The latter is reacted with sodium borohydride to yield p-thiol-alpha-methylbenzyl alcohol which is converted to the diacetate with acetyl chloride. The diacetate is then cracked at 460.degree. C to yield the p-vinylphenyl thioacetate.
Nuyken et al, Polymer Bulletin 4, 75-82 (1981) disclose the preparation of 4-vinylbenzenethiol by a method similar to that taught by Overberger et al discussed previously except that the 4-(1-hydroxyethyl)benzenethiol, i.e., the p-thiol-alpha-methylbenzyl alcohol, is dehydrated directly at 300.degree. C. using alumina as catalyst to form the 4-vinylbenzenethiol.
The diazonium compounds and xanthates formed during the methods described by Overberger et al and Nuyken et al give rise to explosive hazards and thus may render such methods undesirable.